Wink S4 mini whats the best option for me?

Hi guys sorry to the mods if this is in the wrong place? ive got an S4 gt i19195 and its locked to network 3 in the uk, i am swapping the phone tomorrow and i dont like the network logo on it a large 3 from the company i took the contract from, she has another companies sim so i need to unlock it i did it on another phone months ago but ive forgot so i just need to ask does anyone know where there is a way to unlock this for free and a decent ROM & how to install it please? i know this is a BIG ask and i know these are no brainer questions spamming the forum but please have pitty its late here and ive spent hours trying to search for the right ROM or a way to unlock it im ready for bed im up at 4:30am